Plant for making bags

ABSTRACT

The plant comprises a tube-making machine, a station for forming stacks from the tube sections made by the tube-making machine, a conveyor and a distributor for delivering the stacks to preferably two or more end-laying machines, and a device for removing the stacks of bags made by the end-laying machines. A storage device is disposed between the stack-forming device and the distributing station and serves to receive the stacks of tube sections and to deliver them to the distributing station as required, automatically and independently of the delivery speed and delivery timing of the stack-forming device.

United States Patent [72] inventors Willi Stork Tecklenburg; Walter Franke, Weddel; Ewald Fischer, Braunschweig; Karl Haupt, Wolbeck; Werner Hassman, Lengerich, Germany [21] Appl. No. 729,815

[22] Filed May 16, 1968 [45] Patented Mar. 2, 1971 [73] Assignee Windmoller & Holscher Westphalia, Germany [32] Priority May 22, 1967 [33] Germany [54] PLANT FOR MAKING BAGS 18 Claims, 7 Drawing'Figs.

[52] US. Cl 93/8 [51] Int. Cl B31b 1/00 [50] Field of Search 93/8, 93

[ 56] References Cited UNITED STATES PATENTS 3,374,714 3/1968 Berghgracht 92/8 Primary Examiner-H.A. Killy, Jr. Attorney-Fleit, Gipple & Jacobson delivering the stacks to preferably two or more end-laying machines, and a device for removing the stacks of bags made by the end-laying machines. A storage device is disposed between the stack-forming device and the distributing station and serves to receive the stacks of tube sections and to deliver them to the distributing station as required, automatically and independently of the delivery speed and delivery timing of the stack-forming device.

Patented March 2,1971 3,566,754

5 Sheets-Sheet l FIG.1

Patented March 2, 1971 5 Sheets-Sheet z Patented March 2, 1971 3,566,754

5 Sheets-Sheet 4.

Patented March 2, 1971 5 Sheets-Sheet 5 PLANT FOR MAKING BAGS This invention relates to a plant for making bags, particularly from paper, which plant comprises a tube-making machine, a station for forming stacks from the tube sections made by the tube-making machine, a conveyor and a distributor for delivering the stacks to preferably two or more end-laying machines, and a device for removing the stacks of bags made by the end-layingv machines.

It is known from the German Pat. No. 1,150,567 to use a deflector for feeding the tube-sections coming from the tubemaking machine and piled up to form stacks of a predeter mined height to two end-forming machines in alternation. In that machine, the finished tube sections are. delivered by a deflector to two separate conveyor belts, from which they slide onto respective inclined receiving tables, on which they are collected in such a manner that tube sections are collected in a predetermined number on one receiving table and then in thesame number on the other. As the tube sections travel transversely in the end-forming machines, the tube sections leaving the tube-making machine in the longitudinal direction must be turned through 90 before they can be fed to the endforming machines. According to the above-mentioned patent specification, this is accomplished in that the several stacks of tube sections formed on the receiving tables are tipped by the latter onto two conveyor belts, which extend transversely to the previous direction of travel, whereafter the stacks are fed to the two end-forming machines. In thisarrangement, the capacity of a tube-making machine, which is about twice that of an end-forming machine, may be fully utilized because two succeeding end-forming machines are fed. by the said feeding device without need for additional, complicated means, such as an intermediate stacking unit, and with elimination of the 1 previously existing need for workers for receiving and stacking the tube sections and for feeding them to the end-forming machines. This plant will be satisfactory in operation if the tube-making machine operates exactly at twice the rate of one end-forming machine. In practice, however, small variations of the working speeds are sometimes inevitable. For instance, the working speed of the tube-makingmachine must be reduced when the'paper supply roll is to be replaced. In the case i of an obstruction in one of the two end-forming machines, a'smooth, continuous operation will no longer be ensured. In the first case, the-working speed of the two endforming machines must be adjusted immediately to the working speed of the tube-making machine because the feeding of the stacks of tubes is slowed down. In the second case, the arriving stacks of tubes must be laid by hand on a table which is disposed beside the two conveyor belts and these stacks may be subsequently used to fill gaps which'may be formed as a result of a higher speed of the end-forming machines.

From the German Pat. No. 1,187,907 it is known to feed the tube sections made in a tube-making machine by means of a deflector, as in accordance with thefirst-mentioned-German Pat. specification, to two conveyor belts disposed one over the other. The tube sections are subsequently stacked and fed to two end-forming machines in the same direction of travel rather than in a direction which is at an angle of 90 to the previous direction of travel. This arrangement results in a saving of space. To this end, transfer devices are disposed at each of those ends of the conveyor belts which are remote from the tube-making machine and disposed one over the other, and these transfer devices comprise each at least two receiving tables, which extend approximately at right angles to each other and are pivotally movable to both'sides. Each receiving table is divided into two tabletop sections, which are rotatably mounted in a frame in such a manner that they can be suddenly swung apart downwardly by suitable drive means. A

further feeding belt is disposed on each side of the conveyor belts arranged one over the other. The transfer device rotates the stacks of tube sections through 90 and deposits them on the feeding belt, which feeds the stacks to an end-formingmachine. Because the two transfer devices can be pivotally moved to both sides and are longitudinally offset, the two feeding belts can be continuously charged with two superimposed stacks of tube sections. This arrangement results in a considerable saving of space and makes more time available for a deposition of the stacks of tube sections onto the feeding belts, particularly during the cycle-"of operations of the machine. On the other hand, a smooth continuous operation is not ensured in the case of a disturbance in one of the two endforming machines.

The Printed Dutch Application No. 65-10-901 discloses another proposal for a smooth manufacture of paper bags. Ac-

cording to that proposal, the tube sections are shingled on a retarding belt and slide over an inclined surface into a upright bin, from which stacks of tube sections are taken by hand and are turned through and introduced into the magazine for feeding an end-forming machine. When the output of the tube-making machine is higher than that of the end-forming machine, the surplus'tube sections can be stored in the bin. That arrangement has the disadvantage that the bin must not exceed a certain height for design reasons,because otherwise the foundation would have to be broken up and a well be driven into the ground. As aresult, the bin has only a relatively small storage capacity. A worker is constantly needed to reduce the speed of the tube-making machine or even to shut it down when an acoustic signal is generated at the bin. Such signal will be generated when there has been an overproduction for a short time because the storage capacity is relatively small. Another great disadvantage resides in that the tube sections which are disposed 'in the bin and on the retarding belt will not be sufficient to feed the end-forming machines during a short stoppage of the tube-making machine so that this will result in a stoppage of the end-forming machines. According to the last-mentioned proposal, each tube-making machine may be succeeded only by one end-forming machine. A particularly great disadvantage resides in the need for continual manual work to remove stacks of tube sections from the bin, turn said stacks through 90 and subsequently place them on the feeder of the end-forming machine.

It is an object of the invention to provide an automatic plant for feeding tube sections coming from a tube-making machine and stacked in stacks of any desired size, and for distributing said stacks as required to one or more end-forming machines for further processing, or to a stacking-device, which plant involves' small manufacturing costs and requires only little space so that it ensures in all cases a smooth, continuous operation without requiring a constant performance of human work.

To accomplish this object, the proposal according to the invention resides primarily in that a storage device is disposed between the device for forming stacks of tube sections and the distributing station and serves to receive the stacks of tube sections and to deliver them to the distributing station as required, automatically and independently of the delivery speed and delivery timing of the stack-forming device. Such storage device ensures that differences between the instantaneous working speeds of the tube-making machine and the end-laying machines will 'be compensated by a temporary stacking of a larger number of stacks or by a temporary supply of the end-forming machines from the supply of stacks of tube sections in the storage device. Hence, an action of an operator is only required when a disturbance prevails for a relatively long time, e.g., because of a failure of one of a plurality of endforming machines being fed, so that the output of the tubemaking machine must be reduced.

In a particularly simple embodiment, the storage device may comprise at least two conveyor chains, which revolve in mutually parallel, vertical planes about coaxial sprocket wheels and have a conveying surface formed by rolls, which are mounted on the chain links for free rotation about axes extending transversely to the direction of travel, and a stop plate may be provided, which is disposed between the storage device and the distributing station and movable to a release position whenever a stack is to be transferred to the distributing station. In this arrangement, the conveyor chains may revolve continuously because the stacks of tube sections are held back by the retaining plate and are not carried along in this case by the conveyor chains because the rollers which carry the stacks are freely rotatable. A stack of tube sections may be taken whenever required from the supply which is formed on the conveying surface and be fed by the distributing station to one of the end-forming machines or a stacking device.

According to another proposal of the invention, the storage device may consist of at least three stack-conveying belts, which are arranged one behind the other and adapted to be driven independently of each other, the first of said stack-conveying belts being adapted to be driven in response to the discharge of stacks from the stack-forming device and the last of said belts being adapted to be driven in response to delivery commands from the distributing station. In this arrangement, it will be desirable if the motors for driving the conveyor belts are adapted to be energized and deenergized by photoelectric sensing means, which sense the transfer points between the delivery conveyor belt of the stack-forming device and the first conveyor belt of the storage device, between successive conveyor belts, and between the last conveyor belt and the distributing station. The photoelectric sensing means may be so connected that the dark signals from each photoelectric sensing means disposed between two conveyor belts energize the means for driving the conveyor belts disposed on opposite sides of the sensed transfer point and that said means are deenergized by the subsequent bright signal. As a result, the stacks of tube sections reaching the trailing end of a conveyor belt of the storage device will automatically initiate their transfer to the succeeding conveyor belt, and the trailing conveyor belt which is empty after the transfer operation will then be stopped whereas the leading conveyor belt will remain energized because the photoelectric sensing means disposed at the next transfer point deliver now a dark signal so that the stacks are conveyed to the last conveyor belt of the storage device. The motor for driving the last conveyor belt is suitably energizable by a dark signal from the photoelectric sensing means disposed between the last but one and last conveyor belts and by a bright signal from the photoelectric sensing means disposed between the last conveyor belt and the distributing station and is deenergizable by the dark signal from the latter photoelectric sensing means and is also energizable by a delivery command from the distributing station. When there are stacks on the last conveyor belt for the delivery to one of the end-laying machines or the stacking device, a delivery command will case a transfer of the leading stack to the distributing station. A subsequent bright signal will cause the operation of the last conveyor belt to be continued until another stack of tube sections is closely before the distributing station and the drive means is stopped unless another delivery command has been received.

To prevent a starting of the last conveyor belt to receive new stacks of tube sections when such stacks are still on said belt, it is a further feature of the invention that the dark signal from the photoelectric sensing means between the last but one and last conveyor belts is blocked by the dark signal from the photoelectric sensing means between the last conveyor belt and the distributing station. An energization of the means for driving the last but one conveyor belt is to be prevented in the case of short-time bright signals from the photoelectric sensing means which succeeds the last conveyor belt, i.e., when the next following stack is moving to the ready position when a stack has been delivered to the distributing station.

To this end, said blocking may be preferably maintained by a delay means, e.g., a time-limit relay, during the above-mentioned short-time bright signals. Besides, switching devices may be provided according to the invention for the means for driving all conveyor belts of the storage device and may be arranged to block the drive means as long as there are stacks on the next succeeding conveyor belt.

According to another proposal of the invention, a coincidence of dark signals from a certain number of photoelectric sensing means disposed at transfer points between conveyor belts may result in the generation of an audible and/or visual signal, which indicates to the operator that the storage device is filled, e.g., to one half of its capacity, and the output of the tube-making machine must be reduced so that the capacity of the storage device will not be exceeded. A coincidence of dark signals from a certain number of photoelectric sensing means may result in an automatic deenergization of the tube-making machine, suitably just before the capacity of the storage device has been exhausted.

According to another proposal of the invention, which is particularly desirable in conjunction with the storage device which has been described hereinbefore but may be used in plants of the kind described first hereinbefore even when such storage device is not provided, and means are required for changing the direction of stack travel by the means for changing the direction of workpiece travel may consist of a series of parallel, spaced-apart rollers, which are disposed in a horizontal plane and adapted to be driven in their peripheral direction, and a plurality of parallel, revolving, endless conveyors, which extend through the spaces between the rollers, the rollers and the endless conveyors being vertically adjustable relative to each other in such a manner that the supporting surface for the stacks is selectively formed either by the surface of the upper course of the conveyors or by the top parts of the peripheral surfaces of the rollers. When it is desired to forward the stacks of workpieces in a new direction of travel, they will be moved first to the middle ofthe device, e.g., by the endless conveyors, which consist preferably of V-belts, and the device for vertical adjustment is then manually or preferably automatically actuated to lift the rollers or lower the conveyor belts so that the rollers effect the forwarding in the direction of travel at 90. When a change in the direction of travel of the stacks is not desired, the respective stack can be forwarded by the conveyor belt and delivered to suitable succeeding conveying means, one of the end-forming machines or a stacking device. The describe device for changing the direction of travel may desirably be included in the stack-forming station and serve to eliminate stacks which contain tube sections that are defective or to be checked. It forms also the distributing station which succeeds the abovedescribed storage device. In this case, the conveyors for forwarding in the changed direction are preferably adapted to be driven in both directions so that the stacks can be selectively distributed to two end-forming machines disposed on opposite sides of the distributing station. These end-forming machines may preferably be provided with automatic transfer devices for a transfer of the stacks of tube sections to their feeders, and the transfer devices may consist of transfer rakes, which have lifting bars that extend between the rollers and for a transfer are adapted to be lifted above the rollers and to be moved transversely to the direction of the travel imparted by the rollers.

It is also proposed by the invention to provide the stackforming stations with lattice conveyors for compacting the loose stacks of workpieces which have been formed on collecting conveyor belts. The invention includes also the proposal that the known and usual double delivery devices of the end-laying machines should be succeeded by conveyor belts which enable a pivotal movement of their plane of conveyance about their rear reversing pulley so as to combine the stacks of tube sections in a common plane of conveyance.

The invention will be explained more fully in the following description with reference to the drawing, which shows an embodiment by way of example.

FIGS. I and 2 show together in side elevation a plant according to the invention without the tube-making machine.

FIGS. 3 and 4 are a top plan view of FIGS. 1 and 2.

FIG. 5 is a side elevation showing an embodiment of the storage device which is only diagrammatically shown in FIGS. 1 to 4.

FIG. 6 is a front elevation showing a device according to the invention for changing the direction of travel and FIG. 7 is a side elevation of F FIG. 6.

From a tube-making machine, not shown in the drawing, in which a tube is made from a material web by folding the web upon itself and bonding its overlapping marginal portions together by means of adhesive, which tube is then cut into individual tube sections, all these operations being effected in a known manner by common means and forming no part of the present invention complete tube sections 4 are fed by a deflector 1 in alternation in predetermined numbers to upper and lower retarding belts 2 and 3. The retarding belts 2, 3 operate in known manner to shingle the tube sections 4. The upper retarding belt 2 is succeeded by a collecting conveyor belt 5 and the lower retarding belt 3 is succeeded by a collecting conveyor belt 6. A pivoted stop 7 is disposed over each collecting conveyor belt. Each tube section 4 is moved against said stop so that loose stacks 8 of tube sections are formed on the collecting conveyor belts S, 6. Each tube section 4 is braked before the stops 7 by means which are not shown and in such a manner that the tube section will have only a small kinetic energy as it impinges on the stop 7 and the cut edges will not be damaged.

Soon after the formation of the stack 8 containing a predetermined number of tube sections and the shifting of the deflector 1, the stops 7 are swung upwardly and the means for driving the respective collecting conveyor belt 5 or 6 are energized at the same time. Alternatively, the collecting conveyor belts may be constantly driven in known manner so that there is no need for a switching mechanism and a potential source of error is eliminated The loose stacks 8 of tube sections are fed by the collecting conveyor belts 5, 6 and upper and lower roller beds 9, 10 to a compacting belt system ll, 12. One pair of compacting belts 11 are associated with the upper roller bed 9 and the other pair of compacting belts are associated with the lower roller bed 10. The compacting belts consist of lattice conveyors and maintain the tube sections under pressure until felting has occurred between the adhesive-covered surface portions so that a good bonding at the longitudinal adhered seams is ensured. The roller beds 9, 10 are adapted to be driven at a higher speed together with the collecting conveyor belt so that the collecting belt is emptied quickly, and are also adapted to be driven synchronously with the compacting belt systems 11, 12 so that the transfer to the compacting belts is effected at the speed of the latter. These two speeds are imparted to the roller beds in alternation.

V'belts 13, which are adapted to be driven, are disposed between adjacent rollers of the roller beds 9. 10 and adapted to be raised and lowered. The V-belts 13 can be raised to lift stacks 8 which contain defective tube sections from the roller beds an to remove them laterally. Such defective tube sections may be formed, e.g., during a replacement of paper rolls. Such stacks of tube sections may be deposited on inspection tables 14 (FIG. 3), which are disposed on one or both sides of the roller beds. The arrangement may be such that a stack of tube sections is automatically transferred to one of the receiving tables 14 when a predetermined number of stacks of tube sections have been conveyed so that the longitudinal and transverse adhered seams of each tube section can be inspected. Alternatively, the arrangement may be such that all stacks of tube sections are delivered to the receiving tables 14, e.g., when gusseted tubes for sewn bags provided with valves are to be made by the tube-making machine in a special production run.

When the several stacks of tube sections have passed through the compacting belt system, they are received by collecting tables 15, 16. The collecting table 15 is associated with the upper pair of compacting belts 11 and the collecting table 16 with the lower pair of compacting belts 12. At the time of the transfer, the collecting tables are tilted to a receiving position, which is shown in the drawing. After the transfer, the collecting table is moved into a horizontal plane first and is then pivotally moved through 90 so that the tube sections which have been longitudinally discharged from the tube-making machine and stacked can be fed, after a rotation through 90, to the end-forming machines, in which a transverse conveyance is effected. The two tabletop sections of the collecting table 16 are then suddenly swung apart downwardly so that the stack 8 of tube sections resting on the tabletop falls freely onto a belt conveyor 17, which is disposed under the tablc. The tables 15 and 16 are preferably controlled in such a manner that the stacks of tube sections fall from both tables approximately at the same time. The pivotal movement of the collecting tables 15 and 16 through 90 may be omitted if the storage device 18, which will be subsequently described, and the two machines for further processing, extend transversely to the direction of travel in the tube-making machine. The stacks 8 of tube sections will then be deposited in their longitudinal direction onto the conveyor belt 17.

When both collecting tables have dropped their stacks onto the conveyor belt 17, the means for driving the conveyor belt are automatically started and the stacks of tube sections are transferred to a storage device 18. To ensure that the storage device 18 can receive as many stacks as possible, the conveyor belt 17 which precedes the storage device is preferably controlled to transfer only double stacks to the storage device. To ensure a formation of double stacks, the stacking table 16 transfers one stack 8 to the conveyor belt 17, and the means for driving the conveyor belt are then started until the stack 8 enters the deposition range from the second stacking table 15., which can now deposit another stack onto the first stack so that only double stacks are transferred to the storage device 18. These double stacks will also be referred to as stacks 8 hereinafter for convenience. The storage device 18 is designed so that individual stacks 8 can be removed with any timing from the end of the storage device opposite to its charging end and the transfer of stacks from the conveyor belt 17 may be effected independently of the timing of the removal of stacks from the storage device.

This object may be accomplished in that the storage device comprises conveyor belts A, B, c, D, and E (FIG. 5), which are arranged one behind the other and are operated as required, e.g., under control by photoelectric sensing means. In this device the conveyance and storage of the stacks can be controlled in such a manner that the stacks will not contact each other and cannot be damaged by mutually exerted pressure.

A distributing station 19 is arranged at the delivery end of the storage device 18. The distributing station consists of a roller bed 20 and a V-belt conveyor 21 having the same direction of travel as the storage device 18. The roller bed 20 and the V-belt conveyor 21 can be raised and lowered relative to each other. For instance, the V-belt conveyor 21 may be used to deposit the stacks on a conveyor belt 22, by which they are transferred to a stacking device 23. In most cases, 3

however, the individual stacks are to be fed to one of two machines further processing, e.g., to end-forming machines 25, which are preceded by feeders 24 (FIG. 4). In this case, the individual stacks are also transferred first to the V-belt conveyor 21. The same is then lowered below the rollers of the roller bed 20 or the rollers are raised above the V-belts so that the stack can be selectively moved to the right or left on the transverse roller bed 20 into range of a transfer rake 26. Such transfer rakes are disposed at each end of the transverse roller bed between the individual rollers and provided with lifting bars 27, which just as the V-belt conveyor 21 lie between the rollers of the roller bed 20. The means for driving and guiding the transfer rakes 26 are designed so that the drive means for reciprocating the rake 26 cause at the same time an up-anddown movement of the lifting bars 27 so that the stacks oftube s'ections lying on the roller bed 20 are engaged from below by the lifting bars 27 and deposited on the respective feeder. During the subsequent return movement of the rake 26, the lifting bars 27 remain below the plane of action of the feeder 24 and,

of the roller bed 20. The feeders 24 serve to single the tube sections 4 of the stacks 8 and to feed them to the end-forming machines 25, which are disposed on both sides of the storage belt. The complete bags leaving the end-forming machines are inspected in an inspecting device, not shown, for correct folding, and are then shingled and subsequently pushed together to form a stack. This may be accomplished in a stacking station which is like the stacking station 113. Each stack of bags is then fed to a two-storeyed compacting belt system 28, 29 (FIGS. 1 and 3), which is adjusted to such a speed that the stacks of bags are slightly spaced apart as they move between the compacting belts.

A belt conveyor 30, 31 is disposed at the end of each pair of compacting belts 28, 29. These belt conveyors 30, 31 are required to ensure that the stacks of bags 8 arriving in two planes are fed together without friction in a plane by a pivotally movable belt 32 (FIG. 1) and can be subsequently delivered onto a table 33, where a manual sampling inspection can be performed. The belt 32 is pivotally movable about the point 35, which is defined by its rear reversing pulley. The pivotal movement is effected by a double-acting compressedair cylinder 41, which is secured to the base 40 of the frame, not shown, for the pivotally movable belt. The piston rod of the cylinder 41 is connected to a crossmember 44, which connects the side members 43 of the frame. By the piston rod 42, pressure or tension is exerted on the frame of the pivotally movable belt in the direction of the double arrow shown on the drawing to effect a pivotal movement of said frame about the point 35 from the position 32 into the position 32 and vice versa. Depending on the kind of bags to be manufactured, the compacting belts 28 and 29 are not required in every case and the pivotally movable belt 32 may directly succeed the double delivery device of the end-forming machine. The tables 33 transfer the stacks 8 of bags to the collecting conveyor belt 34, which may be coupled to an automatic strapping device, not shown, and may lead to a pallet-loading device.

FIG. 5 shows the above-mentioned desirable embodiment of the storage device 18. The stack 8 is dropped by the first collecting table 16 onto the belt 17 and causes a switch, not shown, to energize the motor M 1. Under the action ofa cam wheel control system, the belt 17 is driven until the stack 8 is just under the second table (FIG. 1). The belt 17 stops in this position until the two dropping tables l5, 16 have dropped another stack so that the stack 8 disposed adjacent to the second dropping table 15 is doubled. When this doubling has been effected, the above-mentioned switch causes the motor M 1 to drive the belt 17 until the stack 8 deposited by the first dropping table 16 is in the dropping range of the second dropping table 15. During this transit time, the previously doubled stack has covered the photoelectric cell F 1 so that the motor M 2 has driven the conveyor belt A of the storage device 18 in such a manner that the conveyor belt A moves at the same speed as the conveyor belt 17. Three reflectors 36- 38 are associated with the photoelectric cell F 1 to ensure that the conveyor belt A is driven by the motor M 2 until the doubled stack 8 has bridged the gap between the conveyor belt 17 and the first belt conveyor A of the storage device. This operation is repeated until the conveyor belt A is fully covered with stacks 8 of bags and the photoelectric cell F 2 is darkened by the stack 8 which was deposited first on the conveyor belt A. Each of the photoelectric cells F 2 and the succeeding photoelectric cells F 3 to F 5 has also three reflectors 36-38 associated with it. When the photoelectric cell F 2 is darkened, the motors M 2 and M 3 drive the conveyor belts A and B at a high speed so that all stacks of tube sections 8 disposed on the conveyor belt A are transferred to the conveyor belt B. When the conveyor belt B is then loaded with stacks of tube sections, the photoelectric cell F 2 delivers a bright signal to indicate that the conveyor belt A is ready for the doubled stacks 8 coming from the conveyor belt 17. When the conveyor belt B is fully loaded, the photoelectric cell F 3 is darkened so that the motor M 3 and the motor M 4 for the conveyor belt C are energized and the conveyor belt B transfers the doubled stacks of tube sections to the conveyor belt C. This operation is repeated until the conveyor belt E is fully loaded with stacks 8 of tube sections. Individual stacks are now transferred by the conveyor belt E to the distributing station 19 (FIGS. 2 and 4). The delivery of a single stack is caused by a delivery command from the distributing station. The command may be stored in a storage element until a stack is in its ready position. A wiper relay, not shown, prevents a delivery of more than one stack in response to each delivery command. When the delivery command is applied and the photoelectric cell F 6 cooperating with a reflector 39 is darkened, the belt E is moving slowly until the photoelectric cell F 6 delivers a bright signal. The conveyor belt E moves at high speed over the distance to the next following stack until the photoelectric cell F 6 is darkened again. A time-limit relay, not shown, is interposed to prevent a starting ofthe belt D during this short bright signal from the photoelectric cell F 6. A switching device, not shown, is also provided to prevent an energization of the motor M 5 when the photoelectric cell F 5 associated with the belt D is dark as long as stacks oftube sections are still on the conveyor belt E. The same arrangement is associated with the other parts of the storage device 18, namely, the conveyor belts C, B, and A. To avoid an overfilling of the storage device 18, an audible and/or visual signal will be generated in response to a coincidence of dark signals from photoelectric cells F 5 and F 4. In this case, the operator of the plant must adapt the speed of the tube-making machine to the speed of the end-forming machines 25. When both end-laying machines fail at the same time, the photoelectric cells F 3 and F 2 generate dark signals too. A suitable circuitry is provided to deenergize the tube-making machine automatically when the photoelectric cell F 2 delivers a dark signal together with the other photoelectric cells. Instead of three reflectors 36- 38 associated with each of the photoelectric cells F 1 to F 5, one reflector for each cell may be sufficient if the light beam from the light source disposed on one side of the conveyor belts is inclined to the direction of travel of the belts and falls on a reflector which is disposed in a suitably inclined position on the other side of the belts so that the stacks intersect the light beam at an acute angle.

Instead of the three conveyor belts shown by way of example in the drawing, any desired number of such belts may be provided between the two conveyor belts A and B. The number of belts depends on the desired storage capacity.

FIGS. 6 and 7 show the device provided according to the invention for changing the direction of travel. The device generally designated comprises essentially a roller bed 46 and a belt conveyor 47. The roller bed 46 is composed of a series of rollers 48 arranged one behind the other. The rollers 48 are rotatably mounted in mounting bars 49 and 50 ofthe roller bed frame and are adapted to be driven by means which are not shown. The mounting rails 49 and 50 are mounted on crossmembers 51 and 52. A pair of guide bars 53 and 54 are secured to each of the ends of said crossmembers 51 and 52. The pairs of guide bars 53 and 54 are connected by a crossbar 55 or 56. One end of each of the crossbars 55 and 56 is received by the free end of the short lever arm 57 or 58 of a respective lever 59 or 60. The other end of each of the crossbars 55 and 56 is secured to the free end of a short lever 69. The other end of the lever is pivoted at 70 to parts of the base frame 63. The levers 59 and 60 are also pivoted at 61 and 62, respectively, to parts of the base frame 63. The long lever arm 64 or 65 of each of the levers S9 and 60 is secured at its free end to the piston rod of a double-acting compressed-air cylinder 66, which rests on a crossmember 67 of the base frame 63. The crossbars 55 and 56 are also reciprocable at both ends in respective slots 68 formed in parts of the base frame 63.

For the sake of clearness, the belt conveyor 47 is not shown in FIG. 7 and illustrated only in FIG. 6. It consists essentially of a number of belts 71, preferably V-belts, which extend around belt pulleys 72-74. Of these pulleys, that designated 72 is adapted to be driven by means which are not shown. The belts 71 travel in a horizontal plane which is normally below the plane of action of the roller bed 46 and are disposed between the rollers 48 of said bed. The rollers 72 and 74 are mounted in the base frame 63 by means not shown.

When a stack of tube sections has been conveyed on the roller bed 46 and is to be forwarded, by the belt conveyor 47 transversely to the original direction of travel, compressed air is admitted by means which are not shown to the piston of the compressed-air cylinder 66 so that the piston rod is extended and forces the lever arms 64 and 65 into a substantially straight position, as is indicated by dash-dot lines in FIG. 7. The roller bed frame 49 to 56 is then swung down about points 61, 62, and 70 while the crossbars 55 and 56 slide down in the slots 68. This operation is continued until the plane of action of the roller bed 46 is below the horizontal plane of travel of the belts 71. When the belt conveyor 47 is operated at the same time, the stack of tube sections can now be forwarded at right angles to its original direction of travel.

When a conveyance in the original direction of travel is desired, pressure in the opposite direction is applied to the piston of the double-acting compressed-air cylinder 66 so that the roller bed frame 49 and 56 returns to its original position shown in FIGS. 6 and 7.

The same result can obviously be produced if the means which carry the belt conveyor 47 are pivotally movable, just as has been described for the roller bed frame, whereas the latter is then stationary.

The manufacturing line composed of several units and shown in FIGS. 1 to 5 represents only one of numerous designs of a highly automatic line for making valved bags with the aid of the storage device according to the invention and the device according to the invention for changing the direction of travel of the stacks. The design of the automatic manufacturing line will depend on the operating conditions in each case.

, Specifically, the units provided according to the invention may be used in plants which are much larger than that shown in FIGS. 1 to 5. For instance, two or more tube-making machines may be connected to any desired number of endforming machines, stacking devices and the like by the units according to the invention.

We claim:

1. In a plant for making bags, comprising a tube-making machine and at least two end-forming machines, the improvement comprising means for forming stacks from the tube sections made by said tube-making machine, conveying and distributing means for delivering said stacks of tube sections to said end-forming machines, storage means disposed between said stack-forming means and said conveying and distributing means and adapted to receive said stacks of tube sections and to deliver them to said conveying and distributing means as required, automatically and independently of the delivery speed and delivery timing of said stack-forming means, and means to remove stacks of bags made by said end-forming machines.

2. The improvement of claim 1, wherein said storage means comprises at least three stack-conveying belts arranged one behind the other and means to drive said stack-conveying belts independently of each other, the first one of said stackconveying belts comprising means responsive to the discharge of stacks from said stack-forming means and adapted to cause operation of said drive means for said first stack-conveying belt, and the last one of said stack-conveying belts being adapted to be driven in response to delivery commands from said conveying and distributing means.

3. The improvement of claim 2, wherein said drive means comprise a plurality of motors adapted to be energized and deenergized by photoelectric sensing means (F 1 to F 6), positioned at the transfer points between the delivery conveyor belt (17) of the stack-forming device and the first conveyor belt (A) of the storage device (18), between successive conveyor belts (AE), and between the last conveyor belt (E) and the distributing station (19).

4. The improvement of claim 3, wherein the motors for driving the stack-conveying belts arranged upstream of the last stack-conveying belt are each adapted to be blocked as long as there are stacks on the succeeding stack-conveying belt.

5. The improvement of claim 3, wherein said photoelectric sensing means are responsive to a dark signal or a bright signal caused by the presence and absence, respectively, of one of said stacks of tube sections in the region of said sensing means, and wherein the dark signals from each photoelectric sensing means (F 1-F 6) disposed between two conveyor. belts (17, A-E) energize the means for driving the conveyor belts disposed on opposite sides of the sensed transfer point and that said means are deenergized by the subsequent bright signal.

6. A plant according to claim 5, characterized in that the .motor for driving the last conveyor belt is energized by a dark signal from the photoelectric sensing means disposed between the next to last and last conveyor belts and by a bright signal from the photoelectric sensing means disposed between the last conveyor belt and the distributing station and is deenergizable by the dark signal from the latter photoelectric sensing means and is also energizable by a delivery command from the distributing station.

7. A plant according to claim 6, characterized in that the dark signal from the photoelectric sensing means between the next to last and last conveyor belts is blocked by the dark signal from the photoelectric sensing means between the last conveyor belt and the distributing station.

8. A plant according to claim 7, characterized in that the blocking is maintained by a delay element during short-time bright signals of the photoelectric sensing means succeeding the last conveyor belt.

9. A plant according to claim 5, characterized in that an audible and/or visual signal isjgenerated in response to the coincidence of dark signals from a predetermined number of photoelectric sensing means disposed at transfer points between conveyor belts.

10. A plant according to claim 5, characterized in that the tube-making machine is adapted to be automatically deenergized in response to the coincidence of dark signals from a predetermined number of photoelectric sensing means at transfer points between belt conveyors.

11. In a plant for making bags, comprising a tube-making machine and at least two end-forming machines, the improvement comprising means for forming stacks from the tube sections made by said tube-making machine, conveying and distributing means for delivering said stacks of tube sections to said end-forming machines, means to remove stacks of bags made by said end-forming machines, and means for changing the direction of travel of stacks by said direction changing means comprising a series of parallel, spaced apart rollers which are disposed in a horizontal plane and adapted to be driven their peripheral direction, and a plurality of parallel, revolving, endless conveyors (71), which extend through the spaces between the rollers, the rollers and the endless conveyors being vertically adjustable relative to each other in such a manner that the supporting surface for the stacks (8) is selectively formed either by the surface of the upper course of the conveyors or by the top parts of the peripheral surfaces of the rollers.

12. A plant according to claim 11, characterized in that the endless conveyors consist of conveyor belts, preferably V belts.

13. A plant according to claim 11, characterized in that the stack-forming station includes means for changing the direction of travel in order to reject stacks having tube sections which are defective or to be checked.

14. A plant according to claim 11, characterized in that the distributing station is formed by means for changing direction of travel.

15. A plant according to claim 14, characterized in that the conveyors for conveying in the changed direction are adapted to be driven in both directions and end-forming machines are disposed on both sides of the distributing station.

16. A plant according to claim l4, characterized in that the conveyors for forwarding to the end-forming machine or machines consist of rollers, and transfer rakes are provided, which serve to transfer the stacks of tube sections to the feeders of the end-forming machines and comprise lifting bars 18. A plant according to claim 1, characterized in that the double delivery means of the end-forming machines are succeeded by conveyor belts, which enable a pivotal movement of their plane of conveyance about their rear reversing pulley so as to combine the stacks of tube sections in a common plane of conveyance. 

1. In a plant for making bags, comprising a tube-making machine and at least two end-forming machines, the improvement comprising means for forming stacks from the tube sections made by said tube-making machine, conveying and distributing means for delivering said stacks of tube sections to said end-forming machines, storage means disposed between said stack-forming means and said conveying and distributing means and adapted to receive said stacks of tube sections and to deliver them to said conveying and distributing means as required, automatically and independently of the delivery speed and delivery timing of said stack-forming means, and means to remove stacks of bags made by said end-forming machines.
 2. The improvement of claim 1, wherein said storage means comprises at least three stack-conveying belts arranged one behind the other and means to drive said stack-conveying belts independently of each other, the first one of said stack-conveying belts comprising means responsive to the discharge of stacks from said stack-forming means and adapted to cause operation of said drive means for said first stack-conveying belt, and the last one of said stack-conveying belts being adapted to be driven in response to delivery commands from said conveying and distributing means.
 3. The improvement of claim 2, wherein said drive means comprise a plurality of motors adapted to be energized and deenergized by photoelectric sensing means (F 1 to F 6), positioned at the transfer points between the delivery conveyor belt (17) of the stack-forming device and the first conveyor belt (A) of the storage device (18), between successive conveyor belts (A- E), and between the last conveyor belt (E) and the distributing station (19).
 4. The improvement Of claim 3, wherein the motors for driving the stack-conveying belts arranged upstream of the last stack-conveying belt are each adapted to be blocked as long as there are stacks on the succeeding stack-conveying belt.
 5. The improvement of claim 3, wherein said photoelectric sensing means are responsive to a dark signal or a bright signal caused by the presence and absence, respectively, of one of said stacks of tube sections in the region of said sensing means, and wherein the dark signals from each photoelectric sensing means (F 1- F 6) disposed between two conveyor belts (17, A-E) energize the means for driving the conveyor belts disposed on opposite sides of the sensed transfer point and that said means are deenergized by the subsequent bright signal.
 6. A plant according to claim 5, characterized in that the motor for driving the last conveyor belt is energized by a dark signal from the photoelectric sensing means disposed between the next to last and last conveyor belts and by a bright signal from the photoelectric sensing means disposed between the last conveyor belt and the distributing station and is deenergizable by the dark signal from the latter photoelectric sensing means and is also energizable by a delivery command from the distributing station.
 7. A plant according to claim 6, characterized in that the dark signal from the photoelectric sensing means between the next to last and last conveyor belts is blocked by the dark signal from the photoelectric sensing means between the last conveyor belt and the distributing station.
 8. A plant according to claim 7, characterized in that the blocking is maintained by a delay element during short-time bright signals of the photoelectric sensing means succeeding the last conveyor belt.
 9. A plant according to claim 5, characterized in that an audible and/or visual signal is generated in response to the coincidence of dark signals from a predetermined number of photoelectric sensing means disposed at transfer points between conveyor belts.
 10. A plant according to claim 5, characterized in that the tube-making machine is adapted to be automatically deenergized in response to the coincidence of dark signals from a predetermined number of photoelectric sensing means at transfer points between belt conveyors.
 11. In a plant for making bags, comprising a tube-making machine and at least two end-forming machines, the improvement comprising means for forming stacks from the tube sections made by said tube-making machine, conveying and distributing means for delivering said stacks of tube sections to said end-forming machines, means to remove stacks of bags made by said end-forming machines, and means for changing the direction of travel of stacks by 90*, said direction changing means comprising a series of parallel, spaced apart rollers which are disposed in a horizontal plane and adapted to be driven their peripheral direction, and a plurality of parallel, revolving, endless conveyors (71), which extend through the spaces between the rollers, the rollers and the endless conveyors being vertically adjustable relative to each other in such a manner that the supporting surface for the stacks (8) is selectively formed either by the surface of the upper course of the conveyors or by the top parts of the peripheral surfaces of the rollers.
 12. A plant according to claim 11, characterized in that the endless conveyors consist of conveyor belts, preferably V-belts.
 13. A plant according to claim 11, characterized in that the stack-forming station includes means for changing the direction of travel in order to reject stacks having tube sections which are defective or to be checked.
 14. A plant according to claim 11, characterized in that the distributing station is formed by means for changing direction of travel.
 15. A plant according to claim 14, characterized in that the conveyors for conveying in the changed direction are adapted to be driven in both directions and end-forming machines are disposed on both sides of the distributing station.
 16. A plant according to claim 14, characterized in that the conveyors for forwarding to the end-forming machine or machines consist of rollers, and transfer rakes are provided, which serve to transfer the stacks of tube sections to the feeders of the end-forming machines and comprise lifting bars which extend between the rollers and for a transfer are adapted to be raised above the rollers and moved transversely to the direction of the travel imparted by the rollers.
 17. A plant according to claim 1, characterized in that the stack-forming station comprises lattice conveyors for compacting the loose stacks of workpieces formed on collecting conveyor belts.
 18. A plant according to claim 1, characterized in that the double delivery means of the end-forming machines are succeeded by conveyor belts, which enable a pivotal movement of their plane of conveyance about their rear reversing pulley so as to combine the stacks of tube sections in a common plane of conveyance. 